Variable dielectric phase shifter



June 29, 1965 F. x. LINDER 3,

VARIABLE DIELECTRIC PHASE SHIFTER I Filed April 25, 1961 INVENTOR. "FrzAuK. X. LIHDEE.

"Mel? MAE.

ATTOIZNEY-S United States Patent 3,12,492 VARZABLE DIELECTRZC PHASE SHEFTER Frank X. Linder, Eau Gallic, Fla, assiguor to Melpar, Inc, Falls Church, Va., a corporation of Delaware Filed Apr. 25, 1961, fier- No. M35501 8 illairns. tCl. 3333l) The present invention relates generally to microwave phase shifters and more particularly to a variable phase shifter.

Generally, prior variable phase shifters employ an arrangement of telescoping tubes, longitudinally slidable relative to one another. In order to provide significant phase shift with the prior devices, appreciable movement of the tubes is required. Sliding contacts, which generate a great deal of noise, are required in order to maintain satisfactory electrical connections between the various tubes.

Accordingly, it is an obg'ect of the present invention to provide a new and improved phase shifter for microwave signals, wherein minimum movement of mechanical parts is necessary to obtain the required phase shift. It is another object to provide a variable microwave phase shifter employing fixed rather than sliding contacts.

It is an additional object of the present invention to provide a new and improved variable phase shifter which is inexpensive to manufacture, simple to operate and that employs a minimum of parts.

A further object is to provide a variable microwave phase shifter utilizing a varying width section, movable transverse, i.e. perpendicular, to the direction of signal propagation rather than parallel thereto. Consequently, the phase shifter unit as a whole is maintained in a permanent position with respect to the remainder of the system and there is no need to adjust the physical location of the system when a change in phase is desired.

Basically, the present invention comprises a pair of spaced, elongated conductors, one conductor substantially surrounding the other and serving as the ground plane for the signal applied to the phase shifter unit. An elongated dielectric element, having a cross-section of varying thickness, is disposed between the conductors and is movable transverse thereto. Thus, the velocity of signal propagation is varied depending upon the amount of dielectric introduced between the conductors. Accordingly, the amount of phase shift introduced by the section is determined by the position of the dielectric relative to the conductors.

The above and still further objects, features and advantages of the present invention will become apparent upon consideraiton of the following detailed description of one specific embodiment thereof, especially when taken in conjunction with the accompanying drawings, wherein:

FIGURE 1 is a schematic diagram of a preferred embodiment of the present invention; and

FIGURE 2 is an exploded perspective view of the structure schematically illustrated in FIGURE 1.

FIGURE 1, the schematic diagram illustrating a crossection of a preferred embodiment of the present invention, comprises a variable dimensioned cross section dielectric member 11, constructed of mica or some other suitable material having a dielectric constant of approximately five. The varying width cross section of dielectric 11 is approximately the shape of a pentagon. A slot 12 stealer Patented June 29, 19%5 ice is provided at one of the apexes of the pentagon in which elongated electrical conductor 13 is disposed. Another elongated electrical conductor 14 surrounds dielectric element 11 and serves as the ground plane for a microwave signal source 15 connected between it an conductor 13. The signal propagates in the direction perpendicular to the plane in which the drawing lies and accordingly transverse to the illustrated cross-section of dielectric 11.

Inner conductor 13 is transversely movable relative to the illustrated cross-section of dielectric 11, as-depicted by arrow 16. As conductor 13 is translated from the innermost portion of slot 12, i.e. the left side as viewed on the drawing, to the portion of the slot wholly between the, opposite sides of conductor 14, the capacity between conductors 13 and 14- is decreased and the section goes from a fully loaded to an air loaded condition. With conductor 13 situated in proximity to the ramp portions 17 of dielectric 11, the capacitance betweenconductors l3 and 14 is some intermediate value between the maximum and minimum values at the slot extremities. The signal coupled between conductors 13 and 14, propagates down the line formed by conductors 13 and 14 at maximum velocity when conductor 13 is located at the irmer portion of dielectric 11 since velocity of propagation is an inverse function of capacity. Since the phase of a signal propagating down a line is a function of propagation velocity, the amount of phase shift introduced in the present unit is dependent upon the transverse position of elongated conductors 13 and 14 relative to dielectric 11.

The change in spacing between conductors 13 and 14 also aids phase shifting properties because increased inductance and capacitance affect phase shift in the same manner. When the maximum dielectric is inserted, resulting in'minirnum capacitance, the conductors 13 and 14 are separated by the greatest extent and the inductance between them is lowest because of the small amount of flux linkages. Opposite conditions prevail when the distance between conductors 13 and id is a minimum. Consequently, inductance and capacitance vary together in the present device and aid each other in achieving the desired phase shift results.

FIGURE 2, an exploded view of a preferred form of the present invention, comprises a metallic, hollow, right parallelepiped 21 having both of its longitudinal sides removed. Fixed metallic conductor 13 is disposed between the opposite faces 22 and 23 of member 21. Conventional coaxial connectors 24 and 25 are fixedly securedto faces 22 and 23, respectively, and provide connections to rod 13 and outer conductors 22 and 23 from a coaxial line. Thesev connectors are provided with insulated interior members 31 so elongated rod 13 is spaced from and not short circuited to member 21.

A further member 27 of substantially the same sizc and shape as the hollow portion of parallelepiped 21 contains a pair of metallic electric conducting sections 28 and 29, having adjacent recessed or ramped portions 32 and 33, respectively, forming a slot which wedge shaped slotted dielectric l1 partially fills. Dielectric it is secured to the adjacent faces of sections 28 and 129 by any suitable means, such asbonding. The slot 12,, between bodies 28 and 29 and the difiering segments of dielectric 11, is located to enable conductor 13 to fit therein when member 27 is inserted into the hollow portion of parallelepiped 21. Since member 27 is slidable within box 21, longitudinally with respect to ends 22 and Z3 and transversely a. to rod 13, the amount of dielectric inserted between the inner and outer elongated conductors may easily be varied. In use, bodies 28 and 29 engage the inner walls of member 21 and are electrically short circuitcd together by faces 22 and 23. Thus, members 22, 23, 28 and 29 substantially surround conductor 13 and serve as the ground plane for the transmitted signal and are represented in FIGURE 1 by conductor 14.

Of course it is understood that any suitable member may be attached to members 21 and 27 to provide an indication of the amount of phase, shift introduced by the unit for any particular frequency.

There has been disclosed herein a variable, microwave phase shifter employing a minimum of moving parts, the movement of which is relatively small to obtain a particular phase shift. No appreciable noise is generated because no sliding contacts are employed.

While I have described and illustrated one specific embodiment of my invention, it will be clear that variations of the details of construction which are specifically illustrated and described may be resorted to without departing from the true spirit and scope of the invention as defined in the appended claims.

What I claim is:

ii. A variable microwave phase shifter comprising a pair of mutually insulated elongated conductors, an elongated diclectric material disposed between said conductors, means for coupling microwave energy to said conductors so the energy propagates longitudinally of said conductors, every cross section of said dielectric at right angles to the energy propagation direction gradually varying in width from one predetermined amount to a second predetermined amount between said pair of conductors, said dielectric being translatable at will relative to one of said conductors in the direction at right angles to the direction of energy propagation, the other of said conductors being mounted for translation with the variable width portion of said dielectric relative to said one conductor in the direction at right angles to the direction of energy propagation to simultaneously change the amount of dielectric between said conductors and the relative spacing of the conductors in the same manner and thereby, gradually vary the capacity and inductance between said conductors at every cross section of said dielectric in the same manner in response to translation of said dielectric.

2. A variable microwave phase shifter comprising a pair of mutually insulated elongated conductors, one of said conductors being substantially surrounded by the other of said conductors, a dielectric material disposed between said conductors, means for coupling microwave energy to said conductors so the energy propagates longitudinally of said conductors, every cross section of said dielectric at right angles to the energy propagation direction gradually varying in Width from one predetermined amount to a second predetermined amount between said pair of conductors, said dielectric being translatable at will relative to said one conductor in the direction at right angles to the direction of energy propagation, the other of said conductors being mounted for translation with the variable Width portion of said dielectric relative to said one conductor in the direction at right angles to the direction of energy propagation to simultaneously change the amount of dielectric between said conductors and the relative spacing of the conductors in the same manner and thereby gradually vary the capacity and inductance between said conductors at every cross section of said dielectric in the same manner in response to translation of said dielectric.

3. The phase shifter of claim 2 wherein said one conductor is fixed, said means for coupling including a pair of fixed contacts the signal carrying terminals of, said contacts connected to opposite ends of said one conductor, the ground plane terminals of said contacts being connccted to opposite sides of said second conductors.

4. A variable microwave phase shifter comprising a first elongated conductor, a second elongated conductor insulated from an substantially surrounding said first conductor, said second conductor including a pair of sections separated by a slot, a slotted dielectric member having a cross-section of varying width carried by adjacent portions of said pair of sections, said dielectric member partially filling the slot between said sections, said first conductor being movable transversely to said second conductor and said cross-section of said dielectric member within the slots of said second conductor and said dielectric member, and means for coupling microwave energy to said conductors so that it propagates longitudinally thereof.

5. A variable microwave phase shifter comprising a first elongated conductor, a second elongated conductor insulated from and substantially surrounding said first conductor, a cross-section of said second conductor including a slot having a ramped portion, a dielectric element secured to the slot of said second conductor, said element including a wedged portion engaging the ramped portion of said second conductor, said element including a slot, said first conductor being transversely movable within the slots of said dielectric and second conductor,

and means for coupling microwave energy to said conductors so that it propagates longitudinally thereof.

6. A variable microwave phase shifter comprising a first elongated conductor, a second elongated conductor insulated from and substantially surrounding said first conductor, said second conductor including a pair of sections separated by a slot, a slotted dielectric member having a cross-section of varying width carried by at least one of said pair of sections, said dielectric member partially filling the slot between said sections, said first conductor being movable transversely to said second conductor and said cross-section of said dielectric member within the slots of said second conductor and said dielectric member, and means for coupling microwave energy to said conductors so that it propagates longitudinally thereof.

7. A variable microwave phase shifter comprising a first elongated signal carrying conductor, a pair of elongated planar ground plane c-onductors connected to each other, said first conductor being insulated from and positioned between said ground plane conductors, means for coupling microwave energy to said conductors so the energy propagates longitudinally to said first and ground plane conductors, an elongated dielectric material disposed between said first conductor and at least one of said ground plane conductors, every cross section of said dielectric material at right angles to the energy propagation direction varying in width from one predetermined amount to a second predetermined amount between said first conductor and at least one or" said ground plane conductors, said dielectric being translatable at will relative to said conductors in the direction at right angles to the direction of energy propagation to vary the phase propagation velocity between said first and ground plane conductors at every cross section of said dieletric.

8. A variable microwave phase shifter comprising a first enlongated signal carrying conductor, an elongated planar ground plane conductor, said first conductor being insulated from and positioned adjacent to said ground plane conductor, means for coupling microwave energy to said conductors so the energy propagates longitudinally to said first and ground plane conductors, an elongated dielectric material disposed between said first conductor and said ground plane conductors, every cross section of said dielectric material at right angles to the energy propagation direction varying in width from one predetermined amount to a second predetermined amount between said first conductor and said ground plane conductors, said dielectric being translatable at will relative to said conductors in the direction at right angles to the direction of energy propagation to vary the phase propagaticm velocity between said first and ground plane conhlctorsv at every cross section of said dielectric.

Refer-2331225 Cited by 1119 Examiner UNITED STATES PATENTS Grieg 33384 Alien 333--31 Hennies et a1 333-98 Fye 33331 French et a1 33331 HERMAN KARL SAALEACH, Primary Examiner.

BENNETT G. MILLER, ELI LIEBERMAN, Examiners. 

1. A VARIABLE MICROWAVE PHASE SHIFTER COMPRISING A PAIR OF MUTUALLY INSULATED ELONGATED CONDUCTORS, AN ELONGATED DIELECTRIC MATERIAL DISPOSED BETWEEN SAID CONDUCTORS, MEANS FOR COUPLING MICROWAVE ENERGY TO SAID CONDUCTORS SO THE ENERGY PROPAGATES LONGITUDINALLY OF SAID CONDUCTORS, EVERY CROSS SECTION OF SAID DIELECTRIC AT RIGHT ANGLES TO THE ENERGY PROPAGATION DIRECTION GRADUALLY VARYING IN WIDTH FROM ONE PREDETERMINED AMOUNT TO A SECOND PREDETERMINED AMOUNT BETWEEN SAID PAIR OF CONDUCTORS, SAID DIELECTRIC BEING TRANSLATE AT WILL RELATIVE TO ONE OF SAID CONDUCTORS IN THE DIRECTION AT RIGHT ANGLES TO THE DIRECTION OF ENERGY PROPAGATION, THE OTHER OF SAID CONCUCTORS BEING MOUNTED FOR TRANSLATION WITH THE VARIABLE WIDTH PORTION OF SAID DIELECTRIC RELATIVE TO SAID ONE CONDUCTOR ON THE DIRECTION AT RIGHT ANGLES TO THE DIRECTION OF ENERGY PROPAGATION TO SIMULTANEOUSLY CHANGE THE AMOUNT OF DIELECTRIC BETWEEN SAID CONDUCTORS AND THE RELATIVE SPACING OF THE CONDUCTORS IN THE SAME MANNER AND THEREBY, GRADUALLY VARY THE CAPACITY AND INDUCTANCE BETWEEN SAID CONDUCTORS AT EVERY CROSS SECTION OF SAID DIELECTRIC IN THE SAME MANNER IN RESPONSE TO TRANSLATION OF SAID ELECTRIC. 